There is a wonderful new history of parliament website
which has biographies of members of parliament going back to 1386. It is a work in progress and there are still many gaps but the site already has over 21,000 biographies. This site also contains the biographical, constituency and introductory survey articles published in The History of Parliament series.
You can search the whole site by keyword. http://www.historyofparliamentonline.org
Thanks to Debbie Kennett at the Guild of One Name Studies for circulating this site.